7 o LIFE AND EXPERIENCES CHAP. 



I asked Faraday if he would allow me the use of 

 the large Grove's battery belonging to the Royal 

 Institution. He sent this down to Manchester, and 

 I remember trying with all my might in the cellars 

 of the old Owens College to throw the image of the 

 spectrum on the screen, but I could not manage it. 

 So I had an accurate reproduction of the drawings 

 which accompanied Bunsen and Kirchhoff's first paper 

 painted on glass. The interesting thing to show 

 was that when a mixture of the salts of the alkali- 

 and of the alkaline-earth metals was placed in the 

 flame, the spectra of the most volatile of these 

 metals made their appearance first ; gradually, how- 

 ever, these died out, and then the spectra of the 

 less volatile became visible. This appearance and 

 disappearance I roughly accomplished by means of 

 two lanterns, as in ordinary dissolving views, and 

 the phenomena were thus clearly understood by 

 everyone present. 



I may here quote a letter which I received from 

 Sir George Stokes in answer to a question as to his 

 share in the history of Solar Chemistry ; it is inter- 

 esting, as it exhibits the modesty of the man and 

 points out clearly the facts which have since then 

 come to light as to the part played by Stokes and 

 Kelvin in the discovery of the coincidence of the dark 

 solar lines with the bright lines of sodium. 



LENSFIELD COTTAGE, CAMBRIDGE, 



7 Feby., 1862. 

 DEAR MR. ROSCOE, 



My share in the history of the Solar Chemistry, I look 

 upon it, is simply nil ; for I never published anything on the 

 subject, and if a man's conversations with his friends are 

 to enter into the history of a subject there is pretty nearly 

 an end of attaching any invention or discovery to any 

 individual. 



